The invention relates to an apparatus and a method for separating the layers of a multi-layered film having at least two laminated layers, a packaging machine comprising this apparatus and a package comprising a cover film consisting of at least two laminated layers.
In the field of meat packaging the problem arises that fresh meat in contact with the oxygen of the air exhibits a red color, but changes to a brown or violet color under exclusion of oxygen, thereby having an unappetizing appearance. The conventional skin packages have the meat lying in a tray and covered by an upper or cover film which is sealed to the edge of the tray and coats the meat like a skin. In case that this cover film consists of an oxygen impermeable film, some time after the packaging process the above-mentioned color change of the meat to a brown or violet color will take place. When using an oxygen permeable film for the cover film, the meat will retain the red color or take it on again.
In order to solve this problem, U.S. Pat. No. 5,591,468 proposes to use two overlying separate layers as cover film, the lower layer being oxygen-permeable and the upper layer being oxygen-impermeable. The two layers are sealed to the edge of the package at respective two separate sealing seams. The upper layer can be pulled off immediately before offering the packages for sale, whereby the meat takes on a red color and a hermetic seal of the package up to this point in time is ensured, thereby keeping the quality of the meat. However, the known method and package disadvantageously require the use of two separate film rolls for producing the package and the generation of two separate sealing seams. This renders the entire method complicated and the corresponding apparatus expensive.
European patent application EP 0 721 899 A1 discloses the use, for skin packages, of a cover film consisting of laminated layers. With this known skin package, however, the problem arises that it is difficult to separate the laminated layers from each other and a separate apparatus is required for providing a point of impact for separating the upper layer from the lower layer.
It is an object of the invention to provide an improved apparatus and method for separating the layers of a multi-layered film. It is a further object of the invention to provide an improved packaging machine using such a multi-layered film and a package comprising such a multi-layered film. Specifically, it is an object of the invention to provide a package which ensures that the product therein, in particular meat, is kept fresh and which allows, at a desired moment, oxygen to come into contact with the product in an easy manner. It is a still further object of the invention to provide an apparatus for separating a film consisting of at least two laminated layers, and a corresponding method, providing an easy way of separating one layer from the other, whereby this film can be used as cover film in packages. Finally, it is an object of the invention to provide a packaging machine for producing the above-mentioned packages.
In order to achieve the above-mentioned objects, the invention provides an apparatus for separating the layers of a multi-layered film in at least an edge region thereof, the film having a first layer and a second layer bonded to the first layer with a limited bonding strength, the first layer having a portion which projects beyond the second layer, the apparatus comprising means for sealing a defined region of the film from the remaining region thereof, the defined region representing the edge region for separating the layers and including at least part of the projecting portion of the first layer, and means for feeding a pressurized fluid to the defined region.
According to a further aspect the invention provides a method of separating the layers of a multi-layered film in an edge region thereof, the film having a first layer and a second layer bonded to the first layer with a limited bonding strength, the method comprising the steps of clamping the film along a border of the edge region and passing a pressurized fluid through the edge region.
According to a third aspect the invention provides a packaging machine comprising an input side, an output side, a plurality of working stations arranged between the input side and the output side, conveyor means for conveying packages along a conveyor path from the:input side to the output side through the working stations, the packages having product carrying means with a product thereon, means for feeding a cover film onto the packages, the cover film having a first layer and a second layer bonded to the first layer with a limited bonding strength, the first layer having a portion which projects beyond the second layer, and means for separating the first layer from the second layer in a defined region extending across the cover film transversely to the conveyor path.
According to a fourth aspect the invention provides a package comprising a product receiving member having an edge, a product on the product receiving member, and a cover film covering said product and sealed to the edge so as to enclose the product between the product receiving member and the cover film, the cover film being a laminated film having at least two layers bonded to each other with a limited bonding strength and separated from each other at a region adjacent to a lateral edge of the cover film, the cover film projecting beyond the edge of the product receiving member at the separated region.